Composite panel with fire resistant face sheets

ABSTRACT

A fire resistant laminate for application to a core structure ( 12 ) to form a sandwich panel ( 10 ) having fire resistant face sheets ( 14  &amp;  16 ). The laminate includes a fire protection ( 18 ) in which at least one layer of fibers ( 22 ) is embedded within a cured inorganic polymer matrix ( 24 ). The laminate further includes an adhesive layer ( 20 ) for bonding to the core structure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to composite sandwich panelswhich are used in aerospace and other applications where light weightand high strength are required. More particularly, the present inventionis directed to composite sandwich panels which are designed for use inan environment where flame resistance and/or fire protection isrequired.

2. Description of Related Art

Composite sandwich panels are widely used in aerospace and otherindustries where structures are required that are light weight andstrong. The sandwich panels typically include a light weight centralcore structure which is sandwiched between two composite face sheets.The face sheets are adhesively bonded to the core. Various corestructures are presently in use with the two main types being rigid foamand honeycomb. Rigid foam cores are advantageous because the face sheetscontact the foam over a relatively large surface area which insures astrong bond. In many foam cores, the core will fracture before theadhesive bond between the face sheets and the core fails. Somedisadvantages of rigid foam core are that light weight rigid foam is notparticularly strong and the fire or flame resistance of many foams isnot particularly good.

Honeycomb provides a number of advantages over rigid foam cores.Honeycomb cores, in general, provide much greater strength than rigidfoam cores having the same density. One drawback of a honeycomb core isthat the surface area which is available for bonding to the face sheetsis much smaller than for foam cores. The honeycomb cells extendtransversely between the face sheets so that the only surface availablefor bonding to the face sheets is the outer edges of the cells. As aresult, the overall strength of the majority of honeycomb panels issignificantly affected by the strength of the bond between the facesheets and the honeycomb.

Epoxy-based adhesives have been used to bond face sheets to honeycombcores where the structural strength of the panel is important. Forexample, honeycomb sandwich panels used for aircraft flooring and otherhigh stress structures have typically utilized epoxy-based adhesives tobond the face sheets to the honeycomb core. Epoxy-based adhesives tendto burn relatively easily and produce large amounts of smoke. Attemptshave been made to increase the fire resistance of epoxy adhesives byhalogenating the adhesives. However, these attempts have not beenentirely successful.

Phenolic adhesives are inherently more fire resistant than epoxyadhesives. However, phenolic resins do not have the same strong adhesiveproperties found in epoxy resins. As a result, phenolic adhesives havebeen limited to use in honeycomb sandwich panels which are notstructural in nature. Such panels include aircraft interior side walls,ceilings and overhead bins. It was found that certain configurations andcombination of phenolic resins and fire protection agents provide lowflame, smoke and toxicity (FST) panels which have structural strengthswhich are equivalent to prior panels using epoxy-based adhesives. Thisdiscovery is set forth in PCT Application No. US00/06609 which is ownedby the same assignee as the present invention.

In many situations, the flame/heat resistance of a composite panel is ofprimary importance. Making such flame/heat resistant panels isparticularly problematic when the central core is made from low heatresistant materials such as NOMEX® (aramid paper) or cellulose-basedresin impregnated fibers. One approach for thermally protecting suchcores is to make the face sheets resistant to flame and heat. Exemplarycomposite panels which include flame/heat protective face sheets aredisclosed in U.S. Pat. Nos. 4,557,961; 4,299,872; 4,598,007;5,309,690;and 4,037,751. The face sheets described in these patents utilize anorganic polymer resin matrix which includes one or more intumescentmaterials.

Heat resistant composite panels have also been made where the facesheets utilize an inorganic resin matrix. For example, U.S. Pat. No.5,798,307 discloses the preparation of a composite panel in which aNOMEX® core is sandwiched between two face sheets composed of carbonfiber fabric impregnated with an alkali alumino-silicate geopolymericmatrix. In the patent disclosure, no separate adhesive is used to bondthe face sheets to the core. Instead, as is known in the art, theuncured face sheets are applied directly to the core and cured(hardened) in place. As a result, the geopolymeric matrix acts as theadhesive.

SUMMARY OF THE INVENTION

In accordance with the present invention, it was discovered that directapplication of inorganic polymers, including the above-described alkalialumino-silicate geopolymers, to honeycomb cores without prior curingcauses a number of problems. Most significantly, curing of suchinorganic polymers generates moisture which in many instances damagesthe honeycomb core. This is especially true for aramid-based corematerials. Further, the adhesion between such inorganic polymers andhoneycomb cores was found to be poor. It was further discovered that theabove problems could be avoided by first curing the inorganic polymermatrix and then applying an adhesive to the cured face sheet to form alaminate which can be bonded securely to the honeycomb core. It wassuprisingly discovered that a separate adhesive layer could be added toincrease adhesion of the face sheets without adversely affecting theflame/heat resistance of the panel which is obtained when using facesheets that incorporate the inorganic polymer matrix alone.

As a feature of the present invention, it was discovered thatstructurally strong composite sandwich panels can be made utilizingfibers in the face sheets which are embedded in an inorganic polymermatrix. It was found that inorganic polymer resins could be used incombination with suitable fibers to form face sheets which are bonded toa suitable core using an adhesive layer to provide panels which exhibitan exceptional combination of peel resistance and fire performance. Itis the combination which is exceptional, rather than the value of eitherproperty taken alone.

The present invention is based on a fire resistant laminate which can beapplied to a core structure to form a sandwich panel having fireresistant face sheets. The fire resistant laminate includes a fireprotection layer which has an inner surface and an outer surface. Thefire protection layer includes at least one layer of fibers which areembedded in a cured inorganic polymer matrix. The fire protection layerfurther includes an inner layer which is composed of at least a portionof the fiber layer and a sufficient amount of inorganic polymer matrixto provide an adhesive surface. This adhesive surface forms the innersurface of the fire protection layer. The adhesive surface itself is notnecessarily sticky. Rather, the term “adhesive” is used in this contextto connote that the surface is an “easily adhered to” or “easily bondedto” surface. The laminate also includes an adhesive layer which isapplied to the adhesive surface of the fire protection layer. Theadhesive layer, with the attached fire protection layer, is applieddirectly to the face of the core structure to form the composite panel.

The present invention covers fire resistant laminates which include asingle fiber layer or multiple fire layers. In either case, the innerlayer of the fire protection layer includes fibers which are embedded inthe inorganic polymer matrix to form an adhesive surface to which theadhesive layer is applied. The present invention also is directed tosandwich panels which utilize the fire resistant laminates in accordancewith the present invention on either one or both faces of the sandwichcore.

The present invention is particularly well-suited for use in transport,especially the aerospace industry where composite laminates and panelsmust meet certain requirements for weight, strength, flammability, smokeand toxicity.

The above discussed and many other features and attendant advantages ofthe present invention will become better understood by reference to thefollowing detailed description when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of an exemplary honeycomb compositesandwich panel in accordance with the present invention wherein aone-ply fire protection layer is attached to one side of the honeycombcore with an adhesive layer (see top of FIG. 1) and a two-ply fireprotection layer with an adhesive layer attached to the other side (seebottom of FIG. 1).

FIG. 2 is a diagrammatic representation of the formation of afire-resistant laminate in accordance with the present invention whichincludes a two-ply fire protection layer and an adhesive layer.

DETAILED DESCRIPTION THE INVENTION

A composite sandwich panel in accordance with the present invention isshown diagrammatically at 10 in FIG. 1. The sandwich panel 10 includes ahoneycomb core structure 12. Other core structure materials are possibleincluding rigid foam and other lightweight materials commonly used insandwich panels. However, the preferred core structure is honeycomb andthe following detailed description will be limited to a description ofthe present invention as it applies to sandwich panels employinghoneycomb cores. The honeycomb core 12 can be any of the commonhoneycomb materials used in sandwich panels.

The honeycomb 12 may be made from aluminum or other lightweight metal.The invention is especially well suited for use with honeycombs madefrom various composite materials which are less heat resistant thanmetal-based honeycomb. Exemplary honeycomb materials include aramidpaper cores, calendared kraft paper core including blends and glassinematerials, flame retardant phenolic foam cores and metallic coresincluding aluminum foam filled cores. The core may include coatingswhich are applied by dipping the core in an appropriate coating solutionas is known in the art. Coatings may be applied to the core by othertechniques, such as spraying, if desired. Phenolics and geopolymers areexemplary coating materials. Although any number of honeycombconfigurations are possible, the preferred honeycomb configurationemploys hexagonally shaped cells. The wall thicknesses of the honeycombcells may be varied to obtain the desired honeycomb core strength.Preferred honeycomb materials for use in accordance with the presentinvention are made from aramid-based materials such as the materialmarketed under the tradename NOMEX® which is available from DupontChemical Co., Wilmington, Del. Another suitable honeycomb material iskraft paper. Kraft paper is a cellulose-based material.

Particularly preferred core materials are NOMEX® or cellulose-basedmaterials, such as kraft paper, which have been coated with an inorganicpolymer. Preferred inorganic polymers include geopolymers based onalumino-silicates. NOMEX® cores coated with alkali alumino-silicategeopolymers are particularly preferred. The inorganic polymer coatingsare applied to the core surface using any of the known technologiesincluding spraying and dipping. The viscosity of the polymer must becontrolled to provide a uniform coating on the core surfaces withoutplugging the honeycomb cell openings. Viscosity of the polymer is easilycontrolled by varying the solvent (e.g. water) concentration to achievethe desired flow characteristics.

Referring again to FIG. 1, the composite sandwich panel 10 includes twoface sheets shown at 14 and 16, respectively. In the preferredembodiment, the sandwich panel will include face sheets on both sides ofthe honeycomb core. However, the present invention does contemplatesituations where only one face sheet is utilized. In such situations,the honeycomb core may require only one face sheet or may be locatedadjacent to a structural member or other element wherein the use of asecond face sheet is not required. For exemplary purposes, all of thesandwich panels discussed herein will include a face sheet on both sidesof the core.

The face sheets 14 and 16 may be identical or they may have differentconfigurations. For the purpose of aiding in description of theinvention, face sheets 14 and 16 will be described as having differentconfigurations. However, it will be understood that in a preferredembodiment, both face sheets will have the same configuration.

Referring first to face sheet 14, the face sheet includes a fireprotection layer 18 which is bonded to the honeycomb core 12 by adhesivelayer 20. The fire protection layer 18 includes a single fiber layer 22which is preferably asymmetrically embedded in an inorganic polymer,such as a cured alkali alumino-silicate geopolymeric matrix 24. Thefiber layer 22 is embedded such that an outer fire barrier layer 26 isformed which is composed essentially of the alkali alumino-silicategeopolymeric matrix 24. The outer fire barrier 26 may range in thicknessfrom less than a few microns to a few centimeters or more. In situationswhere weight is critical, the outer fire barrier 26 may be no more thana thin exterior polymer coating on fibers 22.

The fire protection layer 18 further includes an inner layer 28 in whichthe fiber layer 22 and alkali alumino-silicate geopolymeric matrix 24provide an adhesive surface 30. It is preferred that the adhesivesurface 30 be a textured surface which is formed by the surfaces of thefiber layer 22 and geopolymeric matrix. The textured surface 30 isespecially well-suited for providing adhesion between the fireprotection layer 18 and the honeycomb core face 32. This adhesion isprovided by way of adhesive layer 20. The texture of the adhesivesurface 30 will be in large part determined by the size, shape and weavepattern of the underlying fiber layer. The particular texture patterncan be varied as desired to achieve optimum levels of bonding.Generally, the fabric is chosen and the inorganic polymer resin isapplied to maximize the surface area of the adhesive surface 30 which isavailable for bonding. In addition, the amount of inorganic polymer usedto impregnate the fabric layer 22 can be limited so that some of thefibers on adhesive surface 30 are not coated with inorganic polymer. Inthis way, portions of the adhesive surface 30 will include exposed fibersurfaces which are bonded directly to the adhesive layer. The amount ofexposed (i.e., uncoated) fiber on adhesive surface 30 may be varied toachieve optimum adhesive bonding of the laminate to the honeycomb core.In general, the amount of exposed fiber surface area as a percentage ofthe total adhesive surface 30 may range from 0 up to 90 percent.Preferably, the exposed fiber surface area will be in a range 10–60percent of the total adhesive surface 30.

The face sheet shown at 16 in FIG. 1 is a preferred fire resistantlaminate. The face sheet 16 includes two fiber layers 34 and 36 whichare asymmetrically embedded in the alkali alumino-silicate geopolymericmatrix 24 to form fire protection layer 38. In the same manner as facesheet 14, the fire protection layer 38 includes outer fire barrier 40and textured surface 42. The fire protection layer 38 is bonded to face44 of honeycomb 12 by way of adhesive layer 46. As represented byphantom lines 48 and 50, the adhesive layer 46 may be made up of threeindividual layers of adhesive which are applied to form a singleadhesive layer 46.

A preferred exemplary process for making a fire resistant laminate inaccordance with the present invention is shown diagrammatically in FIG.2. The exemplary method shown in FIG. 2 is for preparing a two-fiberlayer (i.e. two ply) laminate. It will be understood by those skilled inthe art that the same basic procedure applies for making fire resistantlaminates having more than two fiber layers. Initially, a fiber layer 50is impregnated with a sufficient amount of alkali alumino-silicategeopolymeric or other inorganic polymer resin 52 to form a laminate 54which is completely saturated with resin.

The saturated laminate 54 is then applied to a second layer of fibers 60to form an uncured laminate 62 which has an outer fire barrier layer 64and an inner layer having textured adhesive surface 66. The fire barrierlayer 64 has a lower boundary as shown by phantom line 65. As previouslymentioned, the thickness of fire barrier layer 64 may be less than a fewmicrons up to a few centimeters or more. The thickness of the firebarrier 64 can be varied to achieve different levels of fire resistance.The laminate 62 is cured to form a cured alkali alumino-silicategeopolymeric or other cured inorganic polymer matrix in which fiberlayers 50 and 60 are asymmetrically embedded. As shown in FIG. 2,approximately 50 percent of the adhesive surface 66 is composed ofexposed fibers 60. Alternatively, the fibers 60 may be completelyembedded in resin 52 to form a smooth surface or lesser amounts of resinmay be used to achieve varying degrees of texturing.

Adhesive layers 68 and 70 are then applied to the textured surface 66 inorder to form the final fire resistant laminate shown at 72 which isready for application to a suitable honeycomb core. The laminate 62should be cured completely prior to application of the adhesive layers68 and 70. It was found that moisture which may be produced duringcuring of the inorganic polymers can adversely affect the adhesivelayers. Further, the temperatures (180° C. and higher) required to curesome inorganic polymers are much higher than the temperatures used forcuring adhesive polymers. According, co-curing of the inorganic polymermatrix and the adhesive polymer should be avoided.

The amount of resin 52 which is initially applied to fiber layer 50 ischosen such that when the second layer 60 is applied to the firstlaminate, there is sufficient resin present to only partially impregnatefiber layer 60. The partial impregnation of fiber layer 60 results inthe formation of a textured surface as shown at 66. As previouslymentioned, it is this textured surface of partially exposed fibers whichis believed to enhance the adhesion and peel strength between the facesheet and core material. The textured surface may have varying degreesof texture depending upon the particular fabric being used and theamount of fabric surface which is exposed. The exposed fibers may becompletely “dry” or they may be coated with a thin layer of resin. Theamount of “dry” versus coated exposed fibers may be varied to achieveoptimum adhesion.

The adhesives which may be used to form the adhesive layer include anyof the conventional adhesives used to adhere face sheets to corestructures. Epoxy-based adhesives and phenolic adhesives may be used.Phenolic adhesives are preferred. Suitable exemplary adhesives includephenolic resole resins with dissolved polyurethane, such as ESTATE (B.F.Goodrich Specialty Plastics, Cleveland, Ohio) or BUTVAR (Solutia Inc.,St. Louis, Mo.) which is polyvinyl butyral which can be dissolved inphenolic resole. Another suitable adhesive is a phenolic resole resintoughened with a silicone-based modifier such as GP790D62 available fromGeorgia Pacific (Atlanta, Ga.). Phenolic resole resins with othercompatible thermoplastics are also suitable.

Suitable inorganic polymer matrix materials include geopolymeric resinsand also silico-aluminates comprising fluorine and an alkali metal oralkaline earth metal, e.g. alkaline fluoro-sodiumpoly(sialate-disiloxo), fluoro-potassium poly(sialate-disiloxi), andfluoro-calcium poly(sialate-disiloxi) compositions. The fluorinecontaining compositions are described for example in PCT Publication No.WO 93/19129. Exemplary geopolymeric resins are described in U.S. Pat.No. 5,798,307. Alkali alumino-silicate geopolymeric resins arepreferred. These resins are described in detail in U.S. Pat. No.5,798,307.

Suitable alkali alumino-silicate geopolymeric materials include thosecompositions which, after dehydration, have the formula:yM₂O:Al₂O₃:xSiO₂where x is a value lying between 6.5 and 70, y is a value lying between0.95 and 9.50, and M is either Na, K or a mixture of Na and K. Preferredmaterials are potassium, alumino-silicate geopolymeric matrices asdescribed in “Fire and Materials,” Vol. 21, pgs. 67–73 (1997).Particularly preferred resins are those having the formulaSi₃₂O₉₉H₂₄K₇Al.

The fiber layers used to form the laminates may be woven, unidirectionalor random. Any of the fabric materials typically used to form sandwichpanels may be used. Preferred fiber materials include alkali resistantglass fibers, carbon fibers, ceramic fibers, organic fibers, metal mesh,thermoplastics with the thermal stability to form stable reinforcementand other reinforcing materials known in the art.

Examples of practice are as follows:

Preparation of Inorganic Resin

A water based ‘geopolymer’ resin dispersion was obtained by mixing thefollowing components in a glass flask over ice.

GP102A 338.4 g (potassium silicate solution) Sulveol LN  4.0 g (wettingagent) GPS32B 457.6 g (aluminosilica powder) Raw materials were obtainedfrom Geopolymere SA, France.

The above geopolymer resin dispersion was stored in a freezer atapproximately −20°.

Preparation of Inorganic Resin/Carbon Fabric Skins

41.1 g of the above geopolymer resin dispersion was poured onto a pieceof G803 carbon fabric 300×350 mm (weight 300 grams per square meter) andspread with a coating bar to impregnate the fabric with the resinuniformly. The fabric was turned over and another 41.1 g of resin asspread onto the other side of the fabric in the same way. A dry piece ofG803 fabric cut to the same size was placed on top of theresin-impregnated fabric. G803′ fabric is available from Hexcel Corp.(Duxford, England).

These two pieces of fabric were then cured in a hot press at 80° C. for30 minutes and then 130° C. for 90 minutes, with the dry fabric on topof the resin impregnated fabric. The resulting cured ‘skin’ consisted oftwo layers of impregnated fabric bonded together by the inorganic resin.Additional cured skins were prepared and cured in the same way.

The upper and lower faces of these skins were labeled. The lower face(with the piece of impregnated fabric at the surface) was shiny inappearance, with a continuous film of inorganic resin on the fabricwhich formed the fire barrier layer. The upper face (with the piece ofpreviously dry fabric at the surface) formed the textured surface whichwas mat in appearance. The resin had only partially impregnated thepreviously dry fabric so that unimpregnated dry fibers were left at thesurface. Although no specific measurements of degree of impregnation orpercentage dry fibers were made, the quantity of resin used wascalculated to give approximately 50% impregnation of the upper fabric,and so leave around 50% of the total surface of the upper face as dryfibers.

The cured skins where then dried for approximately 16 hours at 80° C.

Preparation of Sandwich Panels

A film of phenolic adhesive was prepared as follows. Phenolic lacqueridentified as “BSL840”, available from VANTICO (Duxford, England), wascoated onto silicone release paper and dried to give an adhesive filmwith a coating weight of 60 grams per square meter (gsm).

One, two or three layers of adhesive film on silicone release paper wereapplied to the upper (partially impregnated) face of the cured and driedskins prepared as above. Impregnation of the adhesive into the skins wasachieved by applying a hot iron to the backing paper. The paper was thenremoved before applying the next layer of adhesive in the same way. Inthis way, skins with adhesive on one face were prepared.

A piece of 9.6 mm thick honeycomb core was cut to the same size as theskins and dried for 1 hour at 140° C. The honeycomb was a phenolicdipped NOMEX material which is available from Hexcel Corp. (Duxford,England) under the commercial name A1-80-3. A sandwich panel wasprepared by applying one face of the core to the adhesive coated side ofone skin, and the other face of the core to the adhesive coated side asecond skin. This panel was heated at 130° C. for 60 minutes in a hotpress to cure the adhesive layers. After curing, the skins (with shinyresin surfaces outermost) were firmly bonded to the core.

The above described procedure was used to prepare four panels asfollows:

-   Panel A with 60 gsm (1 layer) adhesive applied to each of the two    skins-   Panels B and C with 120 gsm (2 layers) adhesive applied to each of    the two skins-   Panel D with 180 gsm adhesive (3 layers) applied to each of the two    skins    Evaluation of Climbing Drum Peel Adhesion

Panels A, B and D were subjected to the climbing drum peel test foradhesives as described in ASTM designation D1781-76 (re-approved 1986).This test measures the strength of the bond between the face sheet andthe core structure. The results are shown below:

Adhesive Weight Peel Strength Panel BSL 840 (gsm) CDP (N/76 mm) A 60 60B 120 190 D 180 330Panels B and D with at least 120 gsm adhesive had adhesion valuesof >130 N/76 mm. A similar panel prepared without using an adhesivelayer between the skins and the core, and with the skins applied to thecore before curing the skins showed poorer adhesion than any of thepanels above. Accordingly, it is preferred that the laminates be curedbefore being bonded to the core. If no adhesive layer is used, and theskins are cured before applying them to the core, there is no adhesionbetween the skins and the core.Evaluation of OSU Heat Release Rate:

Panel C (with 120 gsm BSL 840 adhesive) was subjected to the Ohio StateUniversity (OSU) heat release test. The Ohio State University (OSU) heatrelease test is described in “Heat Release in Fires” edited by B.Babraushkas and S. J. Grayson; El Sevier Applied Science, Pages 13–17,first edition, 1992. This heat release test measures the heat releasedfor the duration of the test from the moment the specimen is insertedinto a controlled exposure chamber and encompasses the period ofignition and progressive flame involvement of the surface of thespecimen. The measurement tests peak heat release rate and total heatrelease rate. The OSU test results are expressed as Peak Heat ReleaseRate/Total Heat Release Rate for a 2-minute period (Peak HRR/Total HRR,2 min.). Peak HRR is expressed as kW/m² and Total HRR is expressed askWmin/m². The units are usually dropped from the OSU test results sothat they are typically expressed simply as a number ratio (e.g. 20/20).A legal requirement of current aircraft regulations is a maximum levelfor OSU of 65/65. The average values of two OSU heat release tests onPanel C were as follows:

-   -   6.4 kW/m² peak heat release rate    -   3.5 kW.min/m² mean heat release rate over first two minutes of        test        As discussed above, these test results are expressed as an OSU        heat release value of 6.4/3.5 which is significantly and        unexpectedly far below the OSU Standard of 65/65.

The OSU heat release value for Panel C is surprisingly low for a panelwith a combustible phenolic adhesive and Nomex core. The carbon fiberreinforced inorganic resin surface layers of the panel act as aneffective fire barrier to protect the combustible materials inside thepanel. During the 5 minute timescale of the OSU heat release test, theoxidation of the carbon fibers does not appear to contributesignificantly to the heat release of the panel. Thus, panels of thisinvention prepared with 120 gsm adhesive have OSU heat release values<10/10 units and CDP >130 N/76 nm.

Having thus described exemplary embodiments of the present invention, itshould be noted by those skilled in the art that the within disclosuresare exemplary only and that various other alternatives, adaptations andmodifications may be made within the scope of the present invention.Accordingly, the present invention is not limited to the above preferredembodiments, but is only limited by the following claims.

1. A fire resistant laminate comprising: (A) a fire protection layercomprising an inner surface and an outer surface, said fire protectionlayer comprising fibers and a cured inorganic polymer; and (B) anadhesive layer comprising an uncured phenolic adhesive which has beenapplied to said inner surface of said fire protection layer.
 2. A Fireresistant laminate according to claim 1 wherein at least a portion ofsaid fibers are located at said inner surface to provide an innersurface which is textured by said fibers.
 3. A fire resistant laminateaccording to claim 2 wherein said inner surface of said fire protectionlayer comprises exposed fibers which consist essentially of fibers thatare not coated with said cured inorganic polymer.
 4. A fire resistantlaminate according to claim 1 wherein said cured inorganic polymer is analkali aluminosilicate geopolymer.
 5. A fire resistant laminateaccording to claim 1 wherein said cured alkali aluminosilicategeopolymeric matrix comprises a composition after dehydration having theformula:yM₂O:Al₂O₂:xSIO₂ where x is a value lying between 6.5 and 70, y is avalue lying between 0.95 and 9.50 and M is either Na, K or a mixture ofNa and K.
 6. A fire resistant laminate according to claim 1 wherein saidfibers are selected from the group consisting of graphite fibers,ceramic fibers and glass fibers.
 7. A fire resistant laminate accordingto claim 1 wherein said fibers comprise at least two layers of fibers.8. A method for making a fire resistant laminate comprising the stepsof: (A) providing a fire protection layer comprising an inner surfaceand an outer surface, said fire protection layer comprising fibers and acured inorganic polymer; and (B) applying an uncured phenolic adhesivelayer to said inner surface of said fire protection layer.
 9. A methodfor making a fire resistant laminate according to claim 8 wherein atleast a portion of said fibers are located at said inner surface toprovide an inner surface which is textured by said fibers.
 10. A methodfor making a fire resistant laminate according to claim 9 wherein saidinner surface of said fire protection layer comprises exposed fiberswhich consist essentially of fibers that are not coated with said curedinorganic polymer.
 11. A method for making a fire resistant laminateaccording to claim 8 wherein said cured inorganic polymer is an alkalialuminosilicate geopolymer.
 12. A method for preparing a fire resistantlaminate according to claim 11 wherein said cured alkali aluminosilicategeopolymeric matrix comprises a composition after dehydration having theformula:yM₂O:Al₂O₂:xSIO₂ where x is a value lying between 6.5 and 70, y is avalue lying between 0.95 and 9.50 and M is either Na, K or a mixture ofNa and K.
 13. A method for making a fire resistant laminate according toclaim 8 wherein said fibers are selected from the group consisting ofgraphite fibers, ceramic fibers and glass fibers.